Advanced Treatment Of Printing&Dyeing Wastewater By Biological Activated Carbon Process

In this study, an Aerobic Upflow Biological Activated Carbon Reactor was constructed by loading ourpreviously screened mixed fungal flora and activated sludge respecteively on activated carbon particles totreat to the printing and dyeing effluents from conventional physicochemical-biochemical treatment system.The treatment efficiencis were compared with advanced oxydition methods and with the control reactor inwhich only activated carbon particles were filled. The results were as follows: under the conditions of theeffective volume of7.12L, the hydraulic retention time of10-12h, flow rate of0.593L/h, aeration capacityof16L/h, temperature of15-32°C and DO of4-6mg/L, the COD removal rate by fungi-carbon reactor andactivated sludge-carbon reactor reached76%-80%and79%-83%permitting effluent COD of140mg/L-170mg/L and130mg/L-150mg/L, respectively, which was higher than the control reactor. Therewas no significant difference in color removals within the three reactors. The color removal rate was stableat80%permitting an effluent colority of40dillutes during the6months operation in spite of the colorvariation between blue-black, dark khaki, dark brown, etc. in the influents.The printing and dyeing wastewater was also treated by using coagulation and sedimentation, NaClOoxidation and Fenton oxidation methods ant the treatment conditions were optimized. The results indicatedthat the higest COD and color removal rate reached40.32%and50%at the conditions of (KAl(SO4)2300mg/l, pH4.0for coagulation and sedimentation method; COD and color removal of30.87%and75%atconditions of NaClO concentration of1.6mg/l, pH6.0for NaClO oxidation method; COD and colorremoval of81.48%and75%at the conditions of0.8ml/L H2O2, FeSO4150mg/L, pH4for Fentonoxidation method. It is suggested that the biological activated carbon reactor siginificantly more efficientthan NaClO oxidation and coagulation methods, and close to the Fenton oxidation method.The abundance of microbial populations was detected using culture, DAPI dyeing and real time PCRmethods. The results shown that the total microbial number was109-1010/g activated carbon, among whichthe cultivable bacteria, actinomyces and fungi were106-107cfu/g,104-106cfu/g and102-104cfu/g,respectively. However,1012-1014/g of bacteria and105-107/g of fungi were counted by using real timePCR method. Although that, the results through the three methods had the same microbial evolution trendsthat the microbial abundance in the bottom of the reactors was higher than in the upper, and the ratio offungi to bacteria decreased significantly with the reactor operation. The microbial community diversity wastracked by using PCR-DGGE and pyrosequencing methods. The PCR-DGGE results indicated that themicrobial community structures in the three reactors underwent dramatic changes durng operation. The454pyrosequencing results indicated that Proteobacteria、Bacteroidetes、Chloroflexi、Planctomycetes were thedominant population in the three reactors. The similarities of the fungi population were high betweendifferent reactors with95%belonging to Hohenbuehelia in Basidiomycota，and Ascomycota occupying nomore than2%. The seed fungi flora was not present in the fungi-activated carbon reactor at the operation of120day. The concentration of archaea was very low in the seed sludge and in the three reactors and most ofthem are unclassified archaea. Methanomicrobia belonging to Euryarchaeota was detected in pure carbon reactor, fungi-activated carbon reactor and seed activated sludge. Thermoprotei belonging to Crenarchaeotawas detected in activated sludge-activated carbon reactor.